The outgoing United Nations undersecretary general for peacekeeping operations said Tuesday that he expects to see the first wave of a regional protection force to arrive in South Sudan within the next few weeks.

"We are sparing no effort in speeding up, and in the next few weeks you will see the first vanguard of the regional force being deployed here in Juba. And I think that will be a very important signal to know that things are moving ahead," Herve Ladsous said.

Ladsous, who is in Juba on his final visit to South Sudan as the U.N.'s top peacekeeping boss, said the Kiir administration must first silence the guns if a national dialogue is going to work.

Ladsous visited the South Sudanese capital this week along with his successor, Jean-Pierre Lacroix, to meet with President Salva Kiir and other top officials.

FILE - Herve Ladsous, head of the U.N. Department of Peacekeeping Operations, speaks to Security Council representatives in New York, Oct.14, 2014.

Ladsous described security and humanitarian conditions in South Sudan as dire. He said the situation requires a political solution and that the national dialogue Kiir proposed in December is not a solution to South Sudan's problems. The dialogue was supposed to begin early this month, according to Kiir, but a start date has yet to be identified by the government.

"A national dialogue, of course, is most useful held in the context where hostilities had ceased, that there is no more fighting first. Second, that the humanitarian context is not as bad as right now. You know, when people are concerned about their basic livelihoods maybe they don't have so much time to spare for political dialogue," Ladsous said.

Ladsous said the government must drive the national dialogue toward a "great consensus," saying it can be a catalyst for peace. At the same time, he warns that open dialogue is not a substitute for a political solution to end the fighting that continues to grip the country.

In his final visit to Juba, Ladsous — who steps down in 10 days — urged all sides to implement the 2015 peace agreement, noting the U.N. is not pleased that it's been all but ignored.

The U.N. peacekeeping chief said the country's warring parties continue to block aid workers from accessing people in need of humanitarian assistance.

"We have faced a number of impediments in terms of freedom of movement, in terms of getting clearances. Very importantly, the humanitarian actors have been severely impeded in their action on the ground," Ladsous said.

Ladsous said South Sudan is one of those countries around the world where there is a high incidence of humanitarian workers being prevented from doing their work, and where workers are killed while trying to help the most needy.

He said the African Union, the United Nations and other stakeholders of the 2015 peace deal continue to try to engage the warring parties to end the fighting and fully implement the agreement.

Ladsous said when he arrives in New York later this week, he will attend another meeting on the status of regional protection force deployments, which he called "very important."

The forces will consist of several units from Rwanda, Nepal, Bangladesh and Ethiopia, among other countries.